U.S. patent application number 12/408206 was filed with the patent office on 2010-09-23 for continuous fiber reinforced thermoplastic parts with in-situ molded features.
Invention is credited to Raul Ayala, Mark Jennings, Paul Douglas Olson, David Wharton.
Application Number | 20100239856 12/408206 |
Document ID | / |
Family ID | 42737923 |
Filed Date | 2010-09-23 |
United States Patent
Application |
20100239856 |
Kind Code |
A1 |
Olson; Paul Douglas ; et
al. |
September 23, 2010 |
Continuous Fiber Reinforced Thermoplastic Parts With In-Situ Molded
Features
Abstract
A method for producing parts comprising the steps of: preparing
a thermoplastic composite base; preparing build up areas on the
base for in situ molded features to form a kit; inserting the kit
into a compression mold; applying heat and pressure to the kit in
the compression mold; and removing the finished part from the
compression mold.
Inventors: |
Olson; Paul Douglas;
(Camarillo, CA) ; Jennings; Mark; (Newbury Park,
CA) ; Ayala; Raul; (Oxnard, CA) ; Wharton;
David; (Newbury Park, CA) |
Correspondence
Address: |
SHELDON MAK ROSE & ANDERSON PC
100 Corson Street, Third Floor
PASADENA
CA
91103-3842
US
|
Family ID: |
42737923 |
Appl. No.: |
12/408206 |
Filed: |
March 20, 2009 |
Current U.S.
Class: |
428/339 ;
264/258; 428/430; 428/522 |
Current CPC
Class: |
B32B 2260/021 20130101;
B32B 5/022 20130101; B32B 2262/10 20130101; B32B 5/024 20130101;
B32B 5/18 20130101; B32B 2605/12 20130101; B32B 27/322 20130101;
B32B 2262/065 20130101; B32B 2307/748 20130101; B32B 27/365
20130101; B32B 2307/4023 20130101; B32B 2457/00 20130101; B32B
2605/18 20130101; B32B 2509/00 20130101; B32B 27/285 20130101; B32B
2307/718 20130101; B32B 27/288 20130101; B32B 27/32 20130101; B32B
27/281 20130101; B32B 2535/00 20130101; B32B 2605/08 20130101; B32B
3/12 20130101; B32B 27/286 20130101; B32B 7/12 20130101; B32B 5/12
20130101; B32B 27/08 20130101; B32B 27/12 20130101; B32B 2260/046
20130101; B32B 2307/50 20130101; Y10T 428/31935 20150401; B29C
70/465 20130101; B32B 27/302 20130101; B32B 27/34 20130101; B32B
27/308 20130101; B32B 27/36 20130101; B32B 2262/101 20130101; B32B
5/22 20130101; B32B 5/26 20130101; B32B 27/18 20130101; B32B
2262/106 20130101; B32B 2262/0269 20130101; Y10T 428/269 20150115;
Y10T 428/31616 20150401 |
Class at
Publication: |
428/339 ;
264/258; 428/522; 428/430 |
International
Class: |
B32B 17/10 20060101
B32B017/10; B29C 70/40 20060101 B29C070/40; B32B 27/36 20060101
B32B027/36 |
Claims
1. A method for producing parts comprising the steps of: a.
preparing a thermoplastic composite base; b. preparing build up
areas on the base for in situ molded features to form a kit; c.
inserting the kit into a compression mold; d. applying heat and
pressure to the kit in the compression mold; and e. removing the
finished part from the compression mold.
2. The method for producing parts of claim 1 further comprising the
step of attaching the build up areas to the base.
3. The method for producing parts of claim 1 wherein the kit
comprises a plurality of layers of continuous fiber reinforced
thermoplastic tape.
4. The method for producing parts of claim 1 wherein the build up
areas comprise the same thermoplastic composite as the base.
5. The method for producing parts of claim 1 wherein the build up
areas comprise a different thermoplastic composite than the
base.
6. The method for producing parts of claim 1 wherein the kit
comprises: a. a thermoplastic; and b. a continuous fiber.
7. The method for producing parts of claim 6 where the
thermoplastic is selected from the group consisting of polyethylene
terephthalate (PET), acrylonitrile butadiene
styrene-polycarbonate(ABS-PC), polypropylene, polylactic acid
(PLA), polyamide, polyphenylene sulfide) (PPS), polyether imide
(PEI), polybutylene terephthalate (PBT), polyphenylene
ether-polystyrene (PPE+PS) and polyetheretherketone (PEEK).
8. The method for producing parts of claim 6 wherein the continuous
fiber is selected from the group consisting of carbon, glass,
basalt, bast, hemp, flax and Kevlar.
9. The method for producing parts of claim 6 wherein the
thermoplastic is polyethylene terephthalate and the continuous
fiber is carbon.
10. The method for producing parts of claim 1 wherein the heat
applied to the kit in the compression mold is from about
220.degree. C. to about 350.degree. C.
11. The method for producing parts of claim 1 wherein the heat
applied to the kit in the compression mold is from about
220.degree. C. to about 250.degree. C.
12. The method for producing parts of claim 1 wherein the pressure
applied to the kit in the compression mold is from about 200 psi to
about 2000 psi.
13. The method for producing parts of claim 1 wherein the pressure
applied to the kit in the compression mold is from about 500 psi to
about 1500 psi.
14. The method for producing parts of claim 1 wherein the kit
comprises at least one of: a thermoplastic foam sheet, a
thermoplastic honeycomb and a thermoplastic film.
15. A part made using the method of claim 1.
16. A composite part comprising: a. a thermoplastic resin; and b. a
continuous fiber; wherein the part further comprises at least one
continuous fiber reinforced detailed feature.
17. The composite part of claim 16 wherein the at least one
continuous fiber reinforced detailed features has a thickness of
less than about 0.5 inches.
18. The composite part of claim 16 wherein the at least one
continuous fiber reinforced detailed features has a thickness of
less than about 0.1 inch.
19. The composite part of claim 16 wherein the at least one
continuous fiber reinforced detailed features has a thickness of
less than about 0.05 inches.
20. The composite part of claim 16 wherein the thermoplastic resin
is selected from the group consisting of: polyethylene
terephthalate (PET), acrylonitrile butadiene
styrene-polycarbonate(ABS-PC), polypropylene, polylactic acid
(PLA), polyamide, polyphenylene sulfide) (PPS), polyether imide
(PEI), polybutylene terephthalate (PBT), polyphenylene
ether-polystyrene (PPE+PS) and polyetheretherketone (PEEK).
21. The composite part of claim 16 wherein the continuous fiber is
selected from the group consisting of: carbon, glass, basalt, bast,
hemp, flax and Kevlar.
22. The composite part of claim 16 wherein the part is formed from
a kit comprising a plurality of lamina of variably oriented
continuous fibers.
23. The composite part of claim 16 wherein the thermoplastic is
polyethylene terephthalate and the continuous fiber is carbon.
Description
BACKGROUND
[0001] The present invention is directed to thermoplastic parts,
and more particularly to fiber reinforced thermoplastic parts with
in-situ molded features.
[0002] Compression molding is a method of forming an object in
which the molding material is generally preheated and placed in an
open, heated mold cavity. The mold is then closed and pressure is
applied to force the material into contact with all mold areas.
Heat and pressure are maintained until the molding material has
cured or cooled. Compression molding of thermoplastic and thermoset
composites has been used for several years to make several types of
parts. Compression molding is suitable for molding complex,
high-strength fiberglass reinforcements, and it is also known that
advanced composite thermoplastics can be compression molded with
unidirectional tapes, woven fabrics, randomly orientated fiber mat
or chopped strand. Compression molding works well for large thick
parts but is difficult for thin detailed structures, and it is also
known as a lower cost molding method, when compared with other
methods such as injection molding. However, compression molding
often provides poor product consistency and difficulty in
controlling flashing, and it is not suitable for some types of
parts, especially those with intricate detail structure.
[0003] Injection molding is another manufacturing process for
producing objects from thermoplastic and thermosetting plastic
materials. In an injection molding process, material is fed into a
heated barrel, mixed, and forced into a mold cavity where it cools
and hardens to the configuration of the mold cavity. Intricate
parts may be formed with injection molding by preparing a mold that
is precision-machined to form the features of the desired object.
Injection molding is widely used for manufacturing a variety of
parts, from the smallest component to entire body panels of cars.
However, fine, ready for paint finishes on complex parts has proven
difficult to obtain with injection molding.
[0004] Plastic injection molding, composite compression molding,
investment casting and liquid injection molding of non-ferrous
metals have all been used to make complex detailed electronic
enclosures. Each of these processes can make thin detailed
electronic enclosures. However, each makes a part deficient in
detail, strength, stiffness, weight or cost. Plastic parts can be
made that are low cost and very detailed, but the part lacks the
strength and stiffness. Compression molded composite parts can be
strong and stiff but heavier, less detailed and costly. Investment
cast and liquid injection molded parts are heavier, weaker, and
insufficiently stiff.
[0005] Thus, there is a need for a method for producing lighter,
stiffer, stronger parts with injection molding like design details
and a fine, paint ready finish. There is also a need for a method
that allows mass production with the cost advantages ascribed to
high volume fabrication.
SUMMARY
[0006] According to the present invention, there is provided an
improved method for producing lighter, stiffer, stronger parts with
injection molding like design details and a fine, paint ready
finish. In an embodiment, the method for producing parts has the
steps of: preparing a thermoplastic composite base; preparing build
up areas on the base for in situ molded features to form a kit;
inserting the kit into a compression mold; applying heat and
pressure to the kit in the compression mold; and removing the
finished part from the compression mold.
[0007] The build-up areas may be attached to the base prior to
inserting the kit into the compression mold. The kit may have a
plurality of layers of continuous fiber reinforced thermoplastic
tape. The kit may have a thermoplastic foam sheet, a thermoplastic
honeycomb or a thermoplastic film. The build-up areas may comprise
the same thermoplastic composite as the base. Additionally, the
build up areas comprise a different thermoplastic composite than
the base.
[0008] In an embodiment, the kit has a thermoplastic and a
continuous fiber. The thermoplastic may be selected from the group
consisting of polyethylene terephthalate (PET), acrylonitrile
butadiene styrene-polycarbonate(ABS-PC), polypropylene, polylactic
acid (PLA), polyamide, polyphenylene sulfide) (PPS), polyether
imide (PEI), polybutylene terephthalate (PBT), polyphenylene
ether-polystyrene (PPE+PS) and polyetheretherketone (PEEK). The
continuous fiber may be selected from the group consisting of
carbon, glass, basalt, bast, hemp, flax and Kevlar. In a particular
embodiment, the thermoplastic is polyethylene terephthalate and the
continuous fiber is carbon.
[0009] In an embodiment, the heat applied to the kit in the
compression mold is from about 220.degree. C. to about 400.degree.
C. In an additional embodiment, the heat applied to the kit in the
compression mold is from about 220.degree. C. to about 350.degree.
C. In an embodiment, the pressure applied to the kit in the
compression mold is from about 200 psi to about 2000 psi. In an
additional embodiment, the pressure applied to the kit in the
compression mold is from about 500 psi to about 1500 psi.
[0010] The present invention is also directed to a part made using
the method of present invention. In particular, the present
invention, according to an embodiment, is directed to a composite
part having a thermoplastic resin; a continuous fiber and at least
one continuous fiber reinforced detailed feature. The at least one
continuous fiber reinforced detailed features may have a thickness
of less than about 0.5 inches. Additionally, the at least one
continuous fiber reinforced detailed feature may have a thickness
of less than about 0.1 inch. Additionally, the at least one
continuous fiber reinforced detailed feature may have a thickness
of less than about 0.05 inches.
[0011] The thermoplastic resin in the part may be selected from the
group consisting of: polyethylene terephthalate (PET),
acrylonitrile butadiene styrene-polycarbonate(ABS-PC),
polypropylene, polylactic acid (PLA), polyamide, polyphenylene
sulfide) (PPS), polyether imide (PEI), polybutylene terephthalate
(PBT), polyphenylene ether-polystyrene (PPE+PS) and
polyetheretherketone (PEEK). The fiber in the part may be selected
from the group consisting of: carbon, glass, basalt, bast, hemp,
flax and Kevlar. In a particular embodiment, the thermoplastic in
the part is polyethylene terephthalate and the continuous fiber in
the part is carbon. The part may be formed from a kit having a
plurality of lamina of variably oriented fibers.
FIGURES
[0012] These and other features, aspects and advantages of the
present invention will become better understood from the following
description, appended claims, and accompanying figures where:
[0013] FIG. 1 is a flowchart showing a method of making continuous
fiber reinforced thermoplastic parts with in-situ molded features
according to one embodiment of the present invention;
[0014] FIG. 2 is a flowchart illustrating preparation of a
thermoplastic composite laminate usable for making continuous fiber
reinforced thermoplastic parts according to an embodiment of the
present invention;
[0015] FIG. 3 is an exploded view of a thermoplastic composite
laminate usable for making continuous fiber reinforced
thermoplastic parts according to an embodiment of the present
invention;
[0016] FIG. 4 is a perspective view of a kit for making continuous
fiber reinforced thermoplastic parts according to an embodiment of
the present invention;
[0017] FIG. 5 is a cross sectional view of the kit of FIG. 3 taken
along line A-A;
[0018] FIG. 6 is a perspective view of a finished part made
according to the present invention;
[0019] FIG. 7 is an enlarged view of a detailed feature of the
finished part of FIG. 5; and
[0020] FIG. 8 is a cross-sectional view through the detailed
feature of FIG. 6.
DESCRIPTION
[0021] According to one embodiment of the present invention, with
reference to FIG. 1, there is provided a method of making
continuous fiber reinforced thermoplastic parts with in-situ molded
features. The method comprises the steps of: preparing a
thermoplastic composite base 10, preparing build-up areas for
in-situ molded features 12, coupling the build-up areas for in-situ
molded features to the base to form a kit 14, inserting the kit
into a compression mold 16, applying heat and pressure to the kit
in the compression mold 18, and removing the finished part from the
compression mold 20. Following removal of the finished part from
the compression mold, the part may be trimmed, drilled, tapped or
painted as desired.
[0022] As used herein the term "composite" means a solid material
which is composed of two or more substances having different
physical characteristics and in which each substance retains its
identity while contributing desirable properties to the whole. The
present invention, according to various embodiments, uses
composites composed of 1) a thermoplastic resin such as
polyethylene terephthalate (PET), acrylonitrile butadiene
styrene-polycarbonate(ABS-PC), polypropylene, polylactic acid
(PLA), polyamide, polyphenylene sulfide) (PPS), polyether imide
(PEI), polybutylene terephthalate (PBT), polyphenylene
ether-polystyrene (PPE+PS) and polyetheretherketone (PEEK); and 2)
a continuous fiber such as; carbon, glass, basalt, bast, hemp, flax
and Kevlar.RTM.. Thermoplastic resins allow the composite to be
heated and molded within seconds in contrast to thermoset resins
such as epoxy that require heat and a chemical reaction which can
take several minutes. Thermoplastic composites usable in this
invention may include, for example, unidirectional strips,
comingled yarns or fabrics, woven unidirectional tapes or
pre-consolidated fabrics. Discontinuous fiber composites may be
used, but are likely to lead to weaker finished parts.
[0023] The steps of preparing a thermoplastic composite base and
build-up areas will now be considered in more detail with reference
to FIGS. 2 to 8. The thermoplastic composite base may be formed of
strategically placing and stacking layers of material and lightly
consolidating the layers using heat and/or pressure. The layers may
be of the same material or of different materials. Each layer may
be, for example, a thermoplastic composite, compatible foam sheet,
honeycomb or thermoplastic film. Each layer may be strategically
placed to optimize the strength, stiffness and weight of the
finished part. This may include different materials in different
areas of the same layer to provide the different areas with
different properties. The materials are assembled and cut to a
proper volume and shape to fill the mold.
[0024] A flowchart illustrating preparation of a thermoplastic
composite laminate according to an embodiment of the present
invention utilizing continuous fiber reinforced thermoplastic tape
is shown in FIG. 2. The resulting laminate is usable for the base
and/or the build-up portions of the kit. An exploded view of the
different layers in the laminate is shown in FIG. 3. The embodiment
shown in FIGS. 2 and 3, and described below, illustrates an example
of the invention; one of skill in the art will recognize that the
materials used and the thicknesses of the layers may be varied to
achieve desired weights and strength characteristics of the final
product.
[0025] A suitable continuous fiber reinforced thermoplastic tape
may be, for example, a unidirectional PET/Carbon tape which is
0.006'' thick and 50% by weight carbon fiber. A first layer of
continuous fiber reinforced thermoplastic tape is oriented in a
first direction 30. Optionally, the first layer is placed on a
platen and a release layer, such as a polytetrafluoroethylene
(PTFE) glass fabric, is placed between the first layer and the
first platen to prevent sticking of the first layer to the first
platen. A second layer, consisting of continuous fiber reinforced
thermoplastic tape, is stacked on top of the first layer, but in a
perpendicular direction 32. A third layer, consisting of plastic
film that is 0.010'' thick made from the same PET resin, is placed
on top of the second layer, the plastic film having the same
thermoplastic as the CFRT tape of the first and second layers
34.
[0026] A fourth layer, consisting of continuous fiber reinforced
thermoplastic tape, is placed on top of the third layer in the
first direction 36. A fifth layer, consisting of plastic film, is
placed on top of the fourth layer, the plastic film having the same
thermoplastic as the continuous fiber reinforced thermoplastic tape
used in previous layers 38. A sixth layer, consisting of continuous
fiber reinforced thermoplastic tape, is placed on top of the fifth
layer in the perpendicular direction 40. A seventh layer,
consisting of continuous fiber reinforced thermoplastic tape, is
placed on top of the sixth layer in the first direction 42.
Optionally, a release layer, such as a PTFE glass fabric, may be
placed on the seventh layer.
[0027] The layers may be consolidated in 20 seconds using light
contact pressure and heat sufficient to bond the layers together to
form the laminate. The pressure used to consolidate the layers may
vary with the materials used, but with PET is preferably from about
5 to about 50 psi, and more preferably from about 5 to about 15
psi. The heat used to consolidate the layers may vary with the
materials used, but with PET is preferably from about 425.degree.
F. to about 475.degree. F.
[0028] As shown in FIGS. 4 and 5, the laminate described above or
other chosen material for the base is shaped, such as by cutting,
to form a base 46. Build-ups 48 are then placed on top of the base
46. The build-ups 48 may be made from the same material as the base
or from a different material. The use of a plastic film between
layers of fiber reinforced thermoplastic tape, as described above,
and the use of composites with higher thermoplastic resin content
may help the continuous fibers flow into the resulting detailed
features.
[0029] Careful placement of build-up material in areas of in-situ
molding of detailed features, such as a screw boss, support or
standoff, is important to the quality of the finished part. Shorter
strips of continuous fiber reinforced thermoplastics may be used
for the build-up areas with the length being defined by dimensions
of the detailed features so that continuous fiber reinforcement is
provided throughout the detailed features.
[0030] In a preferred embodiment of the present invention, the
build-ups are attached to the base by welding to form the kit. A
heated soldering iron with a large flat tip pressed briefly against
each build-up may be used to attach the build-ups it to the base.
Alternatively, a hot-melt glue can be used as means of attaching
the build up. The hot-melt glue can be of the same thermoplastic
used in the kit. Alternatively, the hot-melt glue can be a
crosslinking polymer. Attaching the build-ups to the base increases
the durability and stability of the kit when the kit is placed in
the compression mold and allows for accurate placement of the
build-ups.
[0031] The kit is then placed in the compression mold. Suitable
compression molding systems are well known in the art. When
applying heat and pressure to the kit while the kit is in the
compression mold, the fiber flows with the thermoplastic resin to
fill the mold to the desired shape. The heat and pressure applied
to the kit in the compression mold depends at least partly on the
thermoplastic composite used for the kit. In an embodiment, the
heat applied to the kit in the compression mold is from about
220.degree. C. to about 350.degree. C., and more preferably from
about 220.degree. C. to about 250.degree. C. In an embodiment, the
pressure applied to the kit in the compression mold is from about
200 psi to about 2000 psi, and more preferably, from about 500 psi
to about 1500 psi.
[0032] The kit of FIGS. 4 and 5 fill the mold and result in the
finished part shown in FIGS. 6 and 7. The finished part is a fiber
reinforced structure that is several times stronger than a similar
structure formed only from thermoplastic resin. Importantly, even
the detailed features of the finished part, such as the boss shown
in FIG. 7, are much stronger than similar structures formed from
only thermoplastic resin. As shown in FIG. 8, the increased
strength of the detailed features is due to continuous fiber
reinforcement of the detailed featured themselves.
[0033] The present invention is also directed to continuous fiber
reinforced thermoplastic parts having continuous fiber reinforced
detailed features. Typical detailed features include bosses,
stand-offs, alignment pins and wave guides. Preferably, at least
one of the continuous fiber reinforced detailed features has a
thickness in at least one dimension of less than about 0.5 inches,
more preferably less than 0.10'' inches and even more preferably
less than about 0.05 inches.
[0034] The methods of the present invention according to specific
embodiments, can be used to efficiently produce many different
kinds of parts. For example, parts can be made for: consumer
products, such as vacuum cleaners; industrial products, such as
cases and housings for electronics as well as fans and vanes;
aircraft, such as seat frame structures and window frames;
recreational products, such as snow board and ski bindings;
automotive products, such as oil pans, seat structures and
dashboard structures; boat products, such as propellers; and
medical products, such as gurney frames. In sum, the present
invention provides for mass production of light weight, stiff, and
strong products with in-situ molded features.
[0035] Although the present invention has been discussed in
considerable detail with reference to certain preferred
embodiments, other embodiments are possible. Therefore, the spirit
and scope of the appended claims should not be limited to the
description of preferred embodiments contained herein.
[0036] All features disclosed in the specification, including the
claims, abstracts and drawings, and all the steps in any method or
process disclosed, may be combined in any combination except
combination where at least some of such features and/or steps are
mutually exclusive. Each feature disclosed in the specification,
including the claims, abstract, and drawings, can be replaced by
alternative features serving the same, equivalent or similar
purpose, unless expressly stated otherwise. Thus, unless expressly
stated otherwise, each feature disclosed is one example only of a
generic series of equivalent or similar features.
[0037] Any element in a claim that does not explicitly state
"means" for performing a specified function or "step" for
performing a specified function, should not be interpreted as a
"means" or "step" clause as specified in 35 U.S.C. .sctn.112.
* * * * *